Over the years, electromechanical relays have found wide and varied application in the communications and electrical arts and have assumed a number of structural forms. In one form, such relays have typically comprised a contact spring assembly for controlling the electrical circuit or circuits in which connected, a coil for generating an operating magnetic field, and a mechanism such as an armature for controlling the spring assembly responsive to the magnetic field. In another form, the relay may comprise a pair of overlapping magnetically responsive reed springs suspended at opposite ends of an enclosing glass envelope, the latter being positioned inside and coaxial with the energizing coil. The springs are operated by the coil generated magnetic field, the flux path for which includes the springs themselves as is well known. In whatever form, electromechanical relays offer many advantages in terms of cost, reliability, and versatility, for example, in circuit applications where the highest operating speed is not a requirement despite their replacement in recent years in some electrical systems by solid state devices. Where the relays are operated in conjunction with the latter devices, which may be extremely small in size, the miniaturization of the relays is also dictated and a number of relays are known which present a minimum profile and require a minimum mounting area.
In each of the relay forms contemplated in the foregoing, the contact springs are operated by the generated magnetic field to close their contacts and, thereby, an electrical circuit, in one case, by means of an intermediate armature, in the other, directly by the field itself. At the termination of the applied field, in the normal case, the contacts are opened by spring action to break the electrical circuit in which connected. In each case, the closure force of the contact springs is directly related to the magnitude of the applied magnetic field. Accordingly, this magnitude and, hence, the power required to operate the relay, must be sufficient to provide adequate closure force. In the past, a number of problems have been encountered in connection with the fabrication and operation of relays employing contact springs which close and open for circuit control. This is particularly true of sealed reed spring relays in which an effective seal between the glass envelope, and the suspended reed contact springs is an added requirement. Spring tension and gap must also be accurately adjusted to ensure reliable operation. The art has also been long concerned with the metallurgy of the actual points of contact of the springs from the viewpoint of erosion resistance. Another concern during relay operation has been that of contact chatter or bounce causing a momentary opening of the circuit before a stable operate state is reached.
It is to the elimination of these and other problems attending the use of contact spring relays that the novel relay structure of this invention is chiefly directed. This objective is simply realized in accordance with the invention by replacing the contact springs of a relay by electrically conductive rollable bodies as circuit completion elements of the character described, for example, in U.S. Pat. No. 2,618,718 of P. Duffing et al., issued Nov. 18, 1952. The contacting arrangement there shown provides for circuit control by the contact and separation of two spherical bodies as the result of the impingement of other spherical bodies. As such, the arrangement is not readily compatible and adaptable for use with present day printed circuit applications.